Plug and socket connections

ABSTRACT

A lamp holder having a plug for engagement in a socket having a plug receiving opening and a plurality of notches communicating with said opening and spaced about the periphery thereof. The leading end of the plug carries a plurality of spaced lugs disposed in cooperating pairs. One lug of each pair is rigid and the other lug is relatively highly flexible. The rigid lug carries an overhanging tang for engaging behind the wall of the socket and the cooperating pairs of lugs are provided with camming surfaces. Upon axial insertion of the plug into the socket aperture and the lugs into the notches, the edges of the notches engage the camming surfaces and automatically rotatably index the plug into a position wherein the overhanging tangs on the rigid lugs locate behind the remote wall of the socket.

United States Patent Curado et al.

PLUG AND SOCKET CONNECTIONS Inventors: Leonard L. Curado, Marshfield Hills; Leonard J. Greshel, Concord; Paul A. Sorensen, Burlington, all of Mass.

Assignee: TRW Inc., Cleveland, Ohio Filed: Nov. 24, 1972 Appl. No.: 309,021

Related U.S. Application Data Continuation-impart of Ser. No. 173,441, Aug. 20, 1971, abandoned.

U.S. Cl. 339/128 Int. Cl H01r 13/32 Field of Search... 339/88, 93, 127, 128, 217 S;

References Cited UNITED STATES PATENTS [4 1 Oct. 14, 1975 3,645,353 2/1972 Cope et al. 339/128 X 3,731,260 5/1973 Nardone et a1. 339/128 Primary ExaminerRichard E. Moore Attorney, Agent, or FirmJames R. OConnor [5 7] ABSTRACT A lamp holder having a plug for engagement in a socket having a plug receiving opening and a plurality of notches communicating with said opening and spaced about the periphery thereof. The leading end of the plug carries a plurality of spaced lugs disposed in cooperating pairs. One lug of each pair is rigid and the other lug is relatively highly flexible. The rigid lug carries an overhanging tang for engaging behind the wall of the socket and the cooperating pairs of lugs are provided with camming surfaces. Upon axial insertion of the plug into the socket aperture and the lugs into the notches, the edges of the notches engage the camming surfaces and automatically rotatably index the plug into a position wherein the overhanging tangs on the rigid lugs locate behind the. remote wall of the socket.

2 Claims, 8 Drawing Figures U.S. Patent Oct. 14, 1975 PLUG AND SOCKET CONNECTIONS CROSS REFERENCE TO RELATED APPLICATION This application is a continuation in part of Application Ser. No. 173,441 filed Aug. 20, 1971 now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates generally to plug and socket connections and more specifically to a plug for such connections which is adapted to be automatically rotatably indexed to a locking position responsive to axial insertion of the plug into the socket. Plug and socket connections of the type contemplated by the invention are frequently found in the prior art relating to electric lamp holder mountings classified in US. Art Class 339 at Subclasses 119+.

2. Description of the Prior Art The prior art is replete with plug and socket connections of the type generally contemplated by the present invention. The oldest and most widely known connections are characterized by a plug having a plurality of circumferential spring fingers which are angularly bent 'to provide radial knuckles for snap engaging in a socket, usually a circular opening in a'supporting member, responsive to axial insertion of the plug into the socket. Since the connection is strictly a snap fastening, the plug is not effectively locked in the socket and is subject to a ready removal responsive to an axial pull or accidental disengagement when subjected to heavy vibration and/or shock. In some instances the spring fingers of the plug have been modified to provide locking tangs or tabs which positively seat behind the remote socket wall and such modified plugs represent an improvement with regard to inhibiting accidental disengagement. The modified plugs, however, suffer the disadvantage of being extremely difficult to remove 'from the socket, even when the remote side of the socket or support member is readily available, for purposes of replacement or repair of the plug or component parts of an assembly embodying the plug.

More recent developments in the art include plugs adapted to be axially telescoped into a socket or sup port member aperture having a central plug receiving portion and one or more circumferential notches communicating with said central portion. The improved plugs are usually provided with radial lugs, the latter frequently having camming surfaces, which are aligned with the notches during insertion and are rotated into engagement with the remote surfaces of the socket or support member between the notches subsequent to axial insertion to complete the coupling. While the latter connections are considered to be an improvement over the earlier designs above mentioned, deliberate rotation of the plug by the installer is required to insure that the camming lugs properly locate behind the socket surfaces and the plugs are subject to accidental disengagement under vibration which often causes incremental rotation in either a clockwise or counterclockwise direction to the extent that the lugs realign with the notches and the plug or an assembly embodying same. e.g.. a lamp holder, drops out of the socket. To overcome the latter deficiency certain of the described plugs have been provided with locking tabs or ribs which seat in one Or more of the notches in the socket when the plug has been fractionally turned from its insertion attitude. The latter plugs have proved effective in inhibiting accidental disengagement responsive to vibratory forces acting on the connection. The locking arrangement is, however, in effect, too positive in that disconnection of the plug from the socket for purposes of replacing or repairing component parts of assemblies embodying the plug is rendered extremely difficult particularly in so-called blind connections wherein the remote side of the socket or support member is concealed and not readily available to one desiring to effect the disconnection.

The present invention is seen to represent a definite improvement over the plug and socket connections above described in that the present plug is adapted to be automatically, rotatably indexed to a locking position responsiveto its axial insertion in an appropriately notched socket; the plug is positively locked in the socket by the seating of the flexible lug of each of its cooperating pairs of lugs in one of the notches in the socket; andthe plug can readily be disengaged from the socket by a combined reverse twist and axial pull deliberately exerted by hand or a convenient tool on an assembly embodying the plug. Thus, the improved connection particularly recommends itself for use in applications wherein the remote side of the socket or a support member mounting or embodying the socket is unavailable at the time the disconnection is to be made.

-A further appreciation of the merits of the invention will be had by one who proceeds to a consideration of the detailed description of the improved plug and socket connection which follows hereinafter. In the description and the accompanying drawing referenced therein, the plug and socket connection is described and depicted in a lamp holder mounting assembly in that it was originally developed for use in assemblies of that typeQThereader will readily appreciate, however, that there are numerous couplings wherein the improved fastening arrangement disclosed can be utilized.

SUMMARY OF THE INVENTION According to the present invention there is provided a plug for engagement in a socket having an aperture for receiving tl'iev plug in a longitudinal direction and having an inner periphery which has formed therein at least one notch bounded at opposite ends thereof by parts defining .first and second end walls of the notch. The plug has for engagement in the notch a pair of adjacent lugs having respectively first and second end surfaces for cooperation with the first and second end walls respectively of the notch, the said surfaces being spaced apart by a distance corresponding to the distance between the said first and second end walls of the notch whereby when the plug is in position in the socket accidental disengagement of the plug from the socket is prevented. One of the lugs (hereinafter referred to as the first lug) is carried rigidly on the plug and has a tang for engaging behind the part of the socket defining the said first end wall of the notch whereby to hold the plug in the socket. The other lug (hereinafter referred to as the second lug) is carried resiliently on the plug in a manner whereby when the plug is engaged in the socket a transverse force applied deliberately to the plug to remove it from the socket results in movement of the lugs in a direction away from the first end wall of the notch, the second lug being de' flected thereby from its normal position and the first lug moving to disengage its tang from behind the said part of the socket defining the first end wall of the notch, whereby the plug may then be withdrawn longitudinally from the socket. Perferably, the second lug is carried on a resilient arm which is itself carried on a post which in turn is carried rigidly on the plug at a position spaced from the second lug in a direction away from the first lug.

According to one preferred feature of the present invention the plug carries a plurality of such pairs of lugs, each pair being arranged for cooperation with a corresonding notch formed in an aperture of a socket with which the plug is intended to be engaged.

In each said pair of lugs the second lug is preferably carried on a resilient arm which is itself carried on a post which in turn is carried rigidly on the plug at a position spaced from the second lug in a direction away from the associated first lug.

Preferably, in each said pair of lugs the said post comprises the rigidly mounted first lug of the next adjacent pair of lugs.

Conveniently, for registration purposes one such pair of lugs is arranged to cooperate with a notch having a dimension between its first and second end walls which is different from that in respect of at least one other notch.

The plug may have a generally circular configuration normal to the said longitudinal direction, and engage with a socket whose aperture is of generally circular configuration.

Preferably, the lugs are chamfered adjacent the said first and second end surfaces whereby to facilitate insertion of the plug longitudinally into a socket.

In one application of the plug it is provided with a generally tubular body in which is carried an electric lamp bulb holder. This tubular body may have a radial flange at one end upon which are carried the lugs.

One plug and socket arrangement, embodying the present invention, for enabling an electric lamp bulb holder to be readily plugged into a supporting structure of an automobile will now be described by way of example and with reference to the accompanying drawmg.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows a plan view of an electrically insulating plug carrying an electric lamp bulb holder;

FIG. 2 shows a longitudinal section through the plug shown in FIG. 1;

FIG. 3 shows an enlarged perspective view of a flanged end of the plug showing a pair of lugs carried thereon;

FIG. 4 shows a side view of an electrical contact assembly which forms part of the lamp bulb holder;

FIG. 5 shows a side view of a tubular casing which forms part of the lamp bulb holder;

FIG. 6 shows a front view of a socket plate having the plug partly engaged in an aperture formed in the socket plate;

FIG. 7 shows a view similar to that of FIG. 6, but with the plug fully engaged in the aperture; and

FIG. 8 shows a part-sectional side view of parts of the plug engaging with cooperating parts of the socket plate.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawingss, the plug and socket arrangement comprises a plug carrying an electric lamp bulb holder and arranged to engage in an apertured socket plate secured on part of an automobile.

The plug includes an annular flange or base 10, surrounding a central aperture 11, and from which extend three integral, curved posts or first lugs 12, 12a and 12b disposed at selected angularly spaced positions around the central aperture 11. The three first lugs 12, 12a and 1212 are all similar in form except that the lug 12a is circumferentially longer than the other two. A curved resilient arm 14 continues circumferentially around the aperture 11 from one end of each of said first lugs. The first lugs are relatively inflexible and rigid. Each resil ient arm 14 is slightly spaced longitudinally from the base 10.

A forwardly facing wall 15 of each of the first or rigid lugs has an engagement portion or tang extending therefrom, the upper surface of which is chamfered so as to provide a cam surface 15. The tang extends only part of the way down the forward wall 15 to provide an engagement shoulder 18. Each resilient arm 14 extending from each first or rigid lug has a free terminal end with a second lug 20 extending radially outwardly therefrom. The rear, upper surface of each second lug 20 is chamfered to provide a leading cam surface 22. Each arm 14 extends toward an adjacent first or rigid lug thereby placing its associated second lug 20 in spaced, proximate relationship with each first or rigid lug, for example, lug 12 as is depicted in FIG. 3.

As is shown best in FIG. 2 the plug also includes a tubular body portion 24 which extends from the base 10, adjacent the edge of the central aperture 11 and on the opposite side of the base 10 from that of the post portions 12. A tubular casing or shell 26, seen best in FIG. 5, is provided within the cavity enclosed by the body portion 24 and is arranged to receive for electrical connection an electric lamp bulb 28. The shell 26 is open at both ends but the opening at one end is restricted by a pair of opposed, inturned shoulders, one of which is notched. The shell 26 has an integral ground terminal 30 extending from the wall at the restricted open end. J-slots are formed internally, on opposite sides of the shell 26, one of the slots being shorter in length longitudinally than the other. (Two equal length .l-slots may be used if desired.)

An electrical connection insert 32 is formed of an organic polymeric material such as general purpose phenolic, modified polyphenylene oxide or polyacetal resin and comprises a body portion generally oval in configuration having a pair of spaced openings 34 formed axially therethrough and having a shoulder portion 36 extending outwardly from each of the long sides of its body portion. A hollow, headed eyelet 38 having a shank portion, a head integral with one end of the shank portion and the other end of the shank portion free, is engaged in each of the openings 34. A compression spring 40 is mounted around the shank portion of each of the eyelets 38 and each shank portion is placed within its respective opening 34 and its free end is then flared outwardly, thus trapping the compression spring 40, between an inteernal, annular shoulder formed in the opening 34 and the head of the eyelet 38, while allowing longitudinal movement of the eyelet 38 within the opening.

The electric lamp bulb holder is assembled by dropping the insert 32 into the shell 26 thereby placing the insert shoulder portions 36 into superposed abutting relation with the inturned shoulders of the shell 26. The

walls of the shell 26 are then dimpled inwardly on opposite sides to abut the upper surfaces of the shoulder portions 36, locking the insert 32 within the shell 26, except for a portion of the insert 32 which extends beyond the shell 26 along side the integral ground terminal 30.

The shell and insert assembly is then engaged in the body portion 24 by press fitting the assembly therein. A portion of the insert 32 extends beyond the body portion 24.

The mounting means for receiving the plug is a socket plate 42 secured, for example, on the body of a motor vehicle at locations designated for the mounting of a lamp housing. The socket plate embodies a central plug receiving aperture 44. Three substantially rectangular notches 46, 48 and 50 having arcuate outer walls are formed around the periphery of the aperture 44. The notches are spaced from each other, and one of the notches 50 is of greater length than either of the other two notches 46, 48.

The connection of the plug to the socket plate 42 is accomplished by axially aligning the plug with the central aperture 44 in the socket and bringing the longer rigid lug 12a and the resilient lug 20 proximate thereto into registration with the longer notch 50 in the socket. This automatically registers the remaining lugs with the other notches by reason of the predetermined relative spacing of same. The plug is then forced longitudinally into the socket. Since each of the notches 46, 48 and 50 is slightly shorter than the corresponding length measured from the forward edge 52 of the cam surface 16 of each rigid lug to the rear edge 54 of the cam surface 22 of the adjacent resilient lug 20 (the aforementioned portions of the plug being best depicted in FIG. 3), the insertion of the plug into the socket causes the arms 14 to deflect inwardly toward the center of the socket aperture by reason of the camming action of the edges of the end walls of the notches on the leading edges 22 and 16 of the resilient and rigid lugs, respectively, as the latter advance into the socket. The resilient lugs 20 are thus moved radially inwardly and toward their adjacent rigid lugs 12, 12a and 1212 until the edges of the aperture 44 and the notches clear the engagement shoulders 18, whereupon the plug automatically rotatably indexes to cause the shoulders 18 to locate behind the remote surfaces of the socket between the notches. This condition is most clearly depicted in FIGS 7 and 8 wherein one will also observe that the forward wall of each of the rigid lugs is disposed closely proximate an end wall of each of the notches. Since the distance from the forward wall 15 of each rigid lug to the rear wall of each resilient lug 20 is less than the corresponding length of each notch, the bias on the arms 14 is released, and the arms retract whereby the resilient lugs 20 effectively fully seat in each of the notches, as is best seen in FIG. 7. The plug is thus locked to the socket plate 42 and will not disengage accidentally therefrom when subjected to shock or heavy vibration, or responsive to the application of a purely axial force exerted thereon.

In order to disengage the plug from the socket plate 42, the plug is deliberately rotated so that each resilient lug 20 is pressed against an end edge of the notch in which it is seated, thereby causing the associated resilient arm 14 to flex inwardly and carry each of the lugs 20 radially inwardly and toward an adjacent rigid lug 12, 12a and 12b. The rotation of the plug likewise causes each engagement shoulder 18 to be moved from behind the remote surfaces of the socket plate 42 and back into registration with the respective notches, thereby permitting the plug to be removed from the socket plate responsive to the simultaneous exertion of an axial force exerted thereon.

We claim:

1. A plug and socket plate combination comprising a socket plate having a central opening and a plurality of peripherally spaced notches communicating with and extending radially outwardly from said central opening and having circumferentially spaced end walls, said plug having a body portion, a radial flange on said body portion for overlying one side of said socket plate, and a plurality of lugs joined to said flange and projecting axially therefrom, said lugs being disposed in circumferentially spaced, cooperating pairs, one lug of each pair being rigidly joined to said flange and having a tang extending circumferentially therefrom in a direction away from the other lug of the pair, said tang being axially spaced from said flange to provide a socket plate engaging shoulder, the other lug of each pair being carried on the end of a resilient arm which is connected to the rigid lug of the next adjacent of said pairs of lugs, each of said pairs of lugs having oppositely facing, circumferentially disposed cam surfaces which engage said end walls of said notches responsive to axial insertion of said plug into said socket plate to automatically rotatably index said plug into a position wherein said shoulders defined by said tangs on said rigid lugs overlie the other surface of said socket plate to retain the plug in assembly with said socket plate.

2. A plug and socket plate combination according to claim 1 wherein the body portion of said plug is generally tubular in configuration and carries an electric 

1. A plug and socket plate combination comprising a socket plate having a central opening and a plurality of peripherally spaced notches communicating with and extending radially outwardly from said central opening and having circumferentially spaced end walls, said plug having a body portion, a radial flange on said body portion for overlying one side of said socket plate, and a plurality of lugs joined to said flange and projecting axially therefrom, said lugs being disposed in circumferentially spaced, cooperating pairs, one lug of each pair being rigidly joined to said flange and having a tang extending circumferentially therefrom in a direction away from the other lug of the pair, said tang being axially spaced from said flange to provide a socket plate engaging shoulder, the other lug of each pair being carried on the end of a resilient arm which is connected to the rigid lug of the next adjacent of said pairs of lugs, each of said pairs of lugs having oppositely facing, circumferentially disposed cam surfaces which engage said end walls of said notches responsive to axial insertion of said plug into said socket plate to automatically rotatably index said plug into a position whereiN said shoulders defined by said tangs on said rigid lugs overlie the other surface of said socket plate to retain the plug in assembly with said socket plate.
 2. A plug and socket plate combination according to claim 1 wherein the body portion of said plug is generally tubular in configuration and carries an electric lamp bulb holder therein. 